On the Universality of Volume-Preserving and Coupling-Based Normalizing Flows

Fuente: arXiv
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Autori principali: Draxler, Felix, Wahl, Stefan, Schnörr, Christoph, Köthe, Ullrich
Natura: Preprint
Pubblicazione: 2024
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author Draxler, Felix
Wahl, Stefan
Schnörr, Christoph
Köthe, Ullrich
author_facet Draxler, Felix
Wahl, Stefan
Schnörr, Christoph
Köthe, Ullrich
contents We present a novel theoretical framework for understanding the expressive power of normalizing flows. Despite their prevalence in scientific applications, a comprehensive understanding of flows remains elusive due to their restricted architectures. Existing theorems fall short as they require the use of arbitrarily ill-conditioned neural networks, limiting practical applicability. We propose a distributional universality theorem for well-conditioned coupling-based normalizing flows such as RealNVP. In addition, we show that volume-preserving normalizing flows are not universal, what distribution they learn instead, and how to fix their expressivity. Our results support the general wisdom that affine and related couplings are expressive and in general outperform volume-preserving flows, bridging a gap between empirical results and theoretical understanding.
format Preprint
id arxiv_https___arxiv_org_abs_2402_06578
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Universality of Volume-Preserving and Coupling-Based Normalizing Flows
Draxler, Felix
Wahl, Stefan
Schnörr, Christoph
Köthe, Ullrich
Machine Learning
We present a novel theoretical framework for understanding the expressive power of normalizing flows. Despite their prevalence in scientific applications, a comprehensive understanding of flows remains elusive due to their restricted architectures. Existing theorems fall short as they require the use of arbitrarily ill-conditioned neural networks, limiting practical applicability. We propose a distributional universality theorem for well-conditioned coupling-based normalizing flows such as RealNVP. In addition, we show that volume-preserving normalizing flows are not universal, what distribution they learn instead, and how to fix their expressivity. Our results support the general wisdom that affine and related couplings are expressive and in general outperform volume-preserving flows, bridging a gap between empirical results and theoretical understanding.
title On the Universality of Volume-Preserving and Coupling-Based Normalizing Flows
topic Machine Learning
url https://arxiv.org/abs/2402.06578